I am studying the taxonomy and biology of marine diatoms. The taxonomy of diatoms is primarily based on the characteristics of the silica shell. These shells or frustules are best studied with the SEM which provides enough depth of focus to permit an interpretation of their complex three dimensional nature. The low voltage SEM that exists at the University of Wisconsin-Madison, IMR for biomedical research provides improved topographical resolution which is essential to distinguish the delicate structural differences between the various species of diatoms. The taxonomic problems for these unicellular algae can, therefore, most effectively be solved with this equipment.